Monday, April 16, 2007

Stem cell study zeroes in on ALS cause


WASHINGTON (Reuters) - Cells that are supposed to nourish and support other nerve cells instead secrete the poisons that cause amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, researchers reported on Sunday.

Two reports published in the journal Nature Neuroscience may show new ways to treat the degenerative nerve disease, which slowly paralyzes its victims until they die.

Both teams showed that the nerve cells called astrocytes, which support and feed neurons, turn toxic when they carry a mutated gene called SOD1, which has been linked with ALS in the past.

Dr. Serge Przedborski of Columbia University in New York and colleagues created mouse motor neuron cells that carried mutated versions of the human superoxide dismutase-1, or SOD1, gene. But these mutated cells did not cause the damage typically seen in ALS when grown in lab dishes of cells.

Then they created astrocytes carrying the mutated human SOD1 gene. Astrocytes are one of the types of glial cells -- support cells in the brain and nervous system that secrete various compounds that nourish neurons.

When SOD1 is mutated in these glial cells, Przedborski and colleagues found, one of the nourishing proteins apparently turns toxic. When they grew astrocytes with mutated SOD1, they killed the neighboring mouse motor neuron cells.

"It was previously thought that astrocytes were merely spectators watching their neighboring motor neurons die," said Przedborski. "With these results, we have learned they are not just spectators, they are major players."

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